I recommend Go Daddy premium and Afternic. Once you get it listed at those two places then do a redirect so that anyone who types the URL goes to one of those two, for-sale pages. I would suggest a price of $500 to $2,000. You might get lucky and attract a buyer in the next year or two. After two years, if it doesn’t sell I would just stop renewing it.
Yes! Selling domain is an emerging trade and no wonder if it can develop into an exchange. www.DomainX.org has been initiated with this view. There are some good ideas in the comments regarding which names to buy and how to grow their value. However one must not forget that it also involves a recurring cost (annual renewal) and keeping many of them might become difficult if you are not really selling at least a few to cover it. Enjoy free listing at DomainX.org.
In theory, you could technically acquire a domain for $10,000 and be able to sell it for $100,000. You could also acquire a domain for $10 and be able to sell it for $100,000, $10,000… or $100, you get the picture. Because of this, it’s hard to recommend a perfect starting budget because your strategy, experience, and the pace at which you learn will hugely affect your buying and selling decisions.